Some kind of weird, janky blue shops with 4x misstep, force, gearhulk, and enough other blue cards to get your force of will count up sounds at least interesting enough to play in a local event. It wouldn't look anything like a real shops list though.

If there was a game winning instant speed (like Enter the Infinite if it allowed sorceries)... because when you're flashing back Ancestral Recall or Dig Through Time you're probably better off putting Griselbrand into play. The only advantage I see in this is that it's easier to hardcast. Firemind's Foresight could get stuff like Ancestral, Time Walk and Yawgmoth's Will, but only if they aren't in the graveyard, so I don't know how reliable that could be.

If there was a game winning instant speed (like Enter the Infinite if it allowed sorceries)... because when you're flashing back Ancestral Recall or Dig Through Time you're probably better off putting Griselbrand into play. The only advantage I see in this is that it's easier to hardcast. Firemind's Foresight could get stuff like Ancestral, Time Walk and Yawgmoth's Will, but only if they aren't in the graveyard, so I don't know how reliable that could be.

I think I overreacted when I said this would be good in colored Shops. Why not just play this in a Drain deck, as a finisher? It's a 5/6 flash AND an artifact (Thirst for Knowledge? Welder?) AND Blue (FoW)

So I've been tinkering with this (pun intended) in a paradoxical outcome deck. Its strong. Very strong. Well worth the 6 CC. I've had it as early as T2 and its a beating. A surprise blocker against mentors or eldrazi can swing the game very easily. I did wish in my first builds that it nabbed sorceries but I've adjusted the deck a bit to be very sorcery-light.

@Soly It could also be worthwhile to use with Flash to get back Paradoxical Outcome for only two mana.

@fsecco The natural pairing with this card seems to be Gifts Ungiven (with honorable mention to Cryptic Command, Tsabo's Decree, and Ad Nauseam). Gifts can have synergy with other graveyard interactions that Oath of Druids enables and also with the Torrential Gearhulk itself. Although it can be Tinkered into play and also exiles to Force of Will I have my doubts that it would be better than what is already commonly used with Oath of Druids strategies. This is mainly because it only interacts with instants and doesn't have flying intrinsically.

If your main plan is to recast a card in your graveyard off of an oath activation Eternal Witness and Snapcaster Mage can accomplish similar tasks without ever being stranded in your hand. They still require you to pay the mana cost of the spell of course but playing higher mana spells like Gifts Ungiven creates a whole other set of issues in deck design by its self. If this were played in an oath deck that deck should probably contain several copies of Mana Drain as well.

The more I think about all the different instants this can re-cast the less certain I am about its interaction with Oath of Druids. Its probably worth testing at the very least. I think the biggest hurtles for a deck like this to overcome will be Flusterstorm and Gush token strategies.